Formation and Bleaching of Color Centers in NaN3

Results of new experiments on low-temperature, photolytically colored sodium azide are presented. By use of a highly monochromatic light source, it has been found possible to bleach one component of the F2+ band and demonstrate the formation of F centers by the released electrons. Thermal bleaching experiments are described which illustrate the presence and lifetime of double anion vacancies. Decomposition of an excited azide ion at a vacancy is postulated as a necessary step in formation of double anion vacancies at low temperature.